Electrically conductive materials are used for a variety of purposes in the fabrication and assembly of electronic devices, integrated circuits, semiconductor devices, passive components, solar cells, solar modules, and/or light emitting diodes.
In general, electrically conductive adhesives (ECAs) provide a mechanical bond between two surfaces and conduct electricity. Typically, ECA formulations are made of a polymer resin filled with electrically conductive metal fillers. The resin generally provides a mechanical bond between two substrates, while the electrically conductive fillers generally provide the desired electrical interconnection.
Typical electrically conductive adhesives require high loadings of electrically conductive fillers which are normally made from expensive conductive metals, such as silver. It is known that the amount of silver can be reduced by using silver-coated metal fillers, e.g. silver-coated copper fillers.
However, the electrical conductivity of adhesive formulations, comprising silver-coated fillers is often significantly reduced compared with formulations based on filler materials made of silver. In addition the stability of formulations containing silver-coated metal fillers is often insufficient at room temperature, which limits the potential use of theses formulations in electronic assembly operations due to thermal instability.
Hence, there is a need for new electrically conductive adhesives that contain a reduced amount of expensive conductive metals, such as silver, and which exhibit a good electrical conductivity and a sufficient stability at room temperature (22° C.).